Iron regulatory protein-2 is an RNA-binding protein that regulates intracellular iron homeostasis at the translational level in mammalian cells. Previous work established that a 73 amino acid motif regulates iron regulatory protein-2 levels through an iron-dependent protein degradation. This oxygen-dependent process probably depends on the interaction of ferric iron with multiple sulfur-containing amino acids in the motif. This project aims to determine: (1) whether a recombinant 73-residue peptide is also sensitive to oxidative modification by an iron-dependent mechanism, thus providing a model of this functional region of the protein; (2) the site and chemical nature of the modified residue in both the recombinant peptide and the full-length protein; and (3) whether fusion of the 73 amino acid motif renders a protein sensitive to iron-triggered degradation. These studies were suspended during most of the year as a result of personnel turnover, but have now resumed. The recombinant peptide has been successfully expressed in bacteria, making available sufficient material to pursue aims (1) and (2). - IRP-2, iron, redox, reactive oxygen species (ROS)